1. Field of the Invention
The present invention relates generally to the treatment of food processing wastes. More particularly, the present invention provides a chemical treatment method that effectively removes fat, blood, tissue and other solids from food processing waste, using novel silicon containing copolymer compositions. These polyelectrolyte compositions are silicon containing copolymers of diallyldimethyl ammonium halides, particularly diallyldimethyl ammonium chloride (DADMAC) and vinyl alkoxysilanes, preferably vinyltrimethoxysilane (VTMS).
2. Description of the Prior Art
Everyday the food processing industry produces many tons of food processing waste. Such food processing waste contaminates the water stream flowing through the food processing system. For example, poultry farm waste water effluents are enriched with fat, oil, blood and other solids from the poultry process. These by-products, such as fat, blood, and tissue, are typically present in the waste water in a range of several hundred to tens of thousands of ppm.
For economic as well as regulatory reasons, the food processing community faces never-ending concerns regarding the disposal and recycling of food processing waste water. The removal of such by-products is critical from an environmental standpoint. In fact, the United States Environmental Protection Agency has placed tight restrictions on total oil and solids content in water that is to be discharged into public drinking water supplies or into open bodies of water.
The removal of such solids is also critical to the established discharge limits for total dissolved solids (TDS), chemical oxygen demand (COD), biological oxygen demand (BOD) and total organic carbon (TOC) into local sewers and rivers. In addition to the EPA's severe discharge limits, food processing industries must also be concerned with local city ordinances.
As an alternative to discharging treated water into a water stream or the like, recycling of the waste back into the processing system provides a cost efficient system. However, in order to recycle such waste water, the solids content and so forth must be effectively removed in order to provide pure water back into the system. Accordingly, the same concerns that are present with respect to the removal of such solids for EPA standards exist for recycling purposes as well.
One of the most effective methods of removing fat, blood, tissue and other solids in waste waters is through the use of chemical aids. Historically, dry polymers and inverse emulsion latexes have been used to treat food processing water. Each material has its own advantages and disadvantages. While dry polymers have the benefit of being extremely concentrated, thereby reducing shipping costs, the equipment to dissolve the polymers is expensive and is not available to all end-users on site. Dry polymers also have a large extent of cross-linking; thus, insoluble, gel materials are present.
Latex polymers also suffer from problems but are used quite frequently. Latex polymer preparations include 30-35% solids dispersed in oil. The latex polymer must be also inverted prior to use. Numerous problems associated with this feeding method have caused many customers to avoid latex polymers. In addition, the latexes generally have a very narrow treating range, often resulting in over-treatment at higher dosages.
Chemicals such as polyethylene oxide, polyethylene amine, polydiallyldimethylammonium chloride and copolymers of acrylamide and quaternized acrylates are specific types of chemical treatments that have been used in the food processing industry. Poly(DADMAC) used to clarify water is disclosed in U.S. Pat. No. 3,409,547. DADMAC/acrylamide copolymers for use in water clarification have been disclosed in U.S. Pat. Nos. 4,869,829; 4,396,513; 4,734,205; and 4,835,234. Hydrophobically modified DADMAC copolymers for the conditioning of food processing waste water have been disclosed in U.S. Pat. No. 5,429,749.
While these chemical treatments have provided a means for removing food, blood, oil and other solids from the waste water, disadvantages exist with the use of such chemical treatments. For example, the above polymers have been traditionally synthesized in an oil solvent, thereby producing an environmentally unfriendly treatment program as well as presenting a potential fire hazard. In addition, chemical treatments incorporating the above polymers contain surfactants. Still further, these prior chemical treatments have a high toxicity thereby preventing the use of such treated waters for recycling purposes or for public drinking water supplies.
Therefore, a need exists for a treatment system that addresses all the environmental concerns presented by food processing waste, while at the same time being environmentally friendly.